A study of voice levels in noise for selection of hearing aids

Abstract

Speech levels and discrimination scores under various noise conditions were studied in fourteen individuals with normal hearing in order to clarify actual communication within noise. The noise conditions of this study consisted of three kinds of different frequency distributions based on three types of representative frequency distributions found in the investigated daily noises. The three kinds of noises were produced by a noise generator through a one-third octave band mixer. The A-weighted noise levels used varied in 10dB steps from 50dB to 90dB. Under these noise conditions, voice levels obtained for face-to-face communication 0.3 meters from talkers uttering Japanese monosyllables were investigated. Speech discrimination scores obtained according to the voice levels were analyzed. Intelligibility of consonants obtained by further analysis of the speech discrimination tests were also investigated. The results indicated that all subjects adjusted the level of his voice and maintained it in accordance with the Aweighted noise level using a normal level of effort; that different noise spectra had no effect on voice level; and that speech discrimination scores and intelligibility of consonants were affected by the frequency distributions of the noises. In selecting hearing aids for those with sensorineural hearing loss, the results of this study should be useful for understanding actual communication in noise and for setting up the test conditions for the selection of a hearing aid with optimum electroacoustic performance.